1. Field of the Invention
This invention relates to an electron microscope such as a scanning electron microscope, a transmission electron microscope, etc., a method for operating the electron microscope, and a computer-readable medium.
2. Description of the Related Art
Nowadays, an electron microscope using an electron lens as well as an optical microscope using an optical lens and a digital microscope is used as an enlargement observation apparatus for enlarging a microbody. The electron microscope is provided by electronically optically designing an image formation system such as an optical microscope as the travel direction of electrons is refracted freely. The available electron microscopes include a transmission electron microscope, a reflection electron microscope, a scanning electron microscope, a surface emission electron microscope (field-ion microscope), and the like. The transmission electron microscope uses an electron lens to form an image of electrons passing through a specimen, a sample, etc. The reflection electron microscope forms an image of electrons reflected on the surface of a specimen. The scanning electron microscope scans a convergent electron beam over the surface of a specimen and uses secondary electrons from the scanning points to form an image. The surface emission electron microscope (field-ion microscope) forms an image of electrons emitted from a specimen by heating or ion application.
The scanning electron microscope (SEM) is an apparatus for using a secondary electron detector, a reflection electron detector, etc., to take out secondary electrons, reflection electrons, etc., occurring upon application of a thin electron beam (electron probe) to an objective specimen and displaying an image on a display screen of a CRT, LCD, etc., for the operator mainly to observe the surface form of the specimen. On the other hand, the transmission electron microscope (TEM) is an apparatus for allowing an electron beam to pass through a thin-film specimen and providing electrons scattered and diffracted by atoms in the specimen at the time as an electron diffraction pattern or a transmission electron-microscopic image, thereby enabling the operator mainly to observe the internal structure of a substance.
When an electron beam is applied to a solid specimen, it passes through the solid by energy of the electrons. At the time, an elastic collision, elastic scattering, and inelastic scattering involving an energy loss are caused by the interaction between the nucleuses and the electrons making up the specimen. As inelastic scattering occurs, the intra-shell electrons of the specimen elements and x-rays, etc., are excited, and secondary electrons are emitted, the energy corresponding thereto is lost. The emission amount of the secondary electrons varies depending on the collision angle. On the other hand, reflection electrons scattered backward by elastic scattering and emitted again from the specimen are emitted in the amount peculiar to the atom number. The scanning electron microscope uses the secondary electrons and the reflection electrons. The scanning electron microscope applies electrons to a specimen and detects the emitted secondary electrons and reflection electrons for forming an observation image.
However, the electron microscope such as SEM or TEM has the disadvantages of a large number of setup items and adjustment items and being difficult to operate as compared with enlargement observation apparatus such as an optical microscope and a digital microscope. Particularly, it is difficult for a beginner unfamiliar with operation of an electron microscope to put the complicated setup items to obtain the best observation image. If an image can be formed, the beginner cannot determine whether or not the image is optimum, and cannot make a fine adjustment to the image, and it is difficult for the beginner even to determine the necessity for the fine adjustment. In some electron microscopes, image observation conditions responsive to the purposes and specimens are preset. However, the beginner cannot recognize the significance of setting the image observation condition based on the characteristics of the electric conductivity, etc., of the specimen, and cannot determine which to select either. Thus, only skilled expert operators would be able to operate electron microscopes. Particularly, an image formed under the setup condition cannot immediately be acquired and thus the operator cannot determine the setup condition while checking the screen, resulting in difficulty in operating the electron microscope.
A general optical microscope involves main adjustment items of specimen positioning, magnification, focus, and brightness, and if the adjustment items are determined, an observation image can be acquired. If each adjustment item is changed, an observation image on which the adjustment item change result is reflected can be provided immediately, so that the operator can change the setting while visually checking the adjustment effect. In contrast, the electron microscope involves various setup and adjustment items and in addition, it is hard to predict what observation image is provided as a result of changing the items, and the operator must check the actually provided image on the screen. In addition, if the setting is changed, it takes time until an image on which the setting change is reflected is provided, and thus the operator cannot check the adjustment effect in real time. For example, with the SEM, while a signal from an arbitrary point on the specimen to be observed is detected, the whole area is scanned and further image processing of the detected signal is performed, thereby forming an image. Thus, it takes time of several ten seconds until one observation image is provided. Therefore, if setting is changed, the above-described operation needs to be again performed from the beginning to acquire an observation image; the operator must wait until an observation image is provided. Thus, the operator cannot promptly check the effect of the setting and it becomes hard for the operator to grasp the effect of setting adjustment on the observation image, resulting in difficulty in operating the electron microscope.
Further, if the acceleration voltage is raised excessively, charge-up occurs and it is made impossible to acquire a normal observation image. In addition, once charge-up occurs, labor to eliminate the charge-up is required; this is also a problem. The problem of charge-up is one factor in making it difficult to operate the electron microscope. Since the electron microscope involves the problems as described above, after all, the operation of the electron microscope depends largely on the experience of the operator, and an electron microscope that can be easily operated by a beginner is expected.
It is therefore an object of the invention to provide an electron microscope provided with a guidance function to facilitate setting the electron microscope, a method for operating n electron microscope, and a computer-readable medium.
In order to accomplish the object above, the following means are adopted. According to a first aspect of the present invention, there is provided an electron microscope for picking up an observation image of a specimen based on an image observation condition, the electron microscope comprising:
a first setting section for setting at least characteristics of the specimen as an image observation condition on a first image observation mode screen;
a first display section for displaying an observation image of the specimen based on the condition set through the first setting section;
a second display section for displaying at least one observation image of the specimen including at least one secondary electron image or at least one reflection electron image under at least two types of image observation conditions based on the condition set through the first setting section; and
a selection section for selecting a desired observation image from among the observation images displayed on the second display section.
The electron microscope according to a second aspect of the present invention is characterized by the fact the second display section displays a plurality of observation images of the specimen including a plurality of secondary electron images in addition to the characteristic according to the first aspect of the present invention.
The electron microscope according to a third aspect of the present invention is characterized by the fact that the second display section displays a plurality o observation images of the specimen including a plurality of reflection electron images in addition to the characteristic according to the first aspect of the present invention.
The electron microscope according to a fourth aspect of the present invention is characterized by the fact that the second display section displays a plurality of the observation images of the specimen including at least one secondary electron image and at least one reflection electron image in addition to the characteristic according to the first aspect of the present invention.
The electron microscope according to a fifth aspect of the present invention is characterized by the fact that it further comprises:
a second setting section for setting at least a spot size of an electron beam on the specimen, an acceleration voltage, a detector type, a specimen position, and an observation magnification as image observation conditions on a second image observation mode screen; and
a mode switch section for switching the first image observation mode screen and the second image observation mode screen, in addition to the characteristic according to the first aspect of the present invention.
The electron microscope according to a sixth aspect of the present invention is characterized by the fact that the at least two types of image observation conditions include at least two types of acceleration voltages or spot sizes changed, in addition to the characteristic according to the first aspect of the present invention.
The electron microscope according to a seventh aspect of the present invention is characterized by the fact that it further comprises:
an observation positioning section for moving the observation image displayed on the first display section to a predetermined position on the first display section; and
an observation magnification change section for changing an observation magnification of the observation image displayed on the first display section,
wherein the second display section displays the at least one observation images of the specimen at the observation position and the observation magnification set through the observation positioning section and the observation magnification change section, in addition to the characteristic according to the first aspect of the present invention.
The predetermined position can be roughly the center of the first display section, for example. The characteristics of the specimen can also be determined based on the electric conductivity of the specimen to be observed.
The electron microscope according to a eighth aspect of the present invention is characterized by the fact that it further comprising:
an adjustment section for adjusting at least any of focus, contrast, or brightness with respect to the observation image selected through the selection section in the first image observation mode, in addition to the characteristic according to the first aspect of the present invention.
The electron microscope according to a ninth aspect of the present invention is characterized by the fact that the at least one secondary electron image includes a secondary electron image acquired with an acceleration voltage set to 5 kV or less and a secondary electron image acquired with an acceleration voltage set to 10 kV or more, in addition to the characteristic according to the first aspect of the present invention.
The electron microscope according to a tenth aspect of the present invention is characterized by the fact that the at least one reflection electron image includes a reflection electron image acquired with an acceleration voltage set to 10 kV or more, in addition to the characteristic according to the first aspect of the present invention.
The electron microscope according to an eleventh aspect of the present invention is characterized by the fact that the acceleration voltage set for each of the secondary electron images or the reflection electron images displayed on the second display section is determined according to a predetermined procedure, in addition to the characteristic according to the first aspect of the present invention.
The electron microscope according to a twelfth aspect of the present invention is characterized by the fact that the second setting section sets an astigmatism to a predetermined value on the second image observation mode screen, in addition to the characteristic according to the fifth aspect of the present invention.
The electron microscope according to a thirteenth aspect of the present invention is characterized by the fact that the second setting section sets an optical axis adjustment on the second image observation mode screen based on a correlation table prepared based on at least the relationship between the acceleration voltage and the spot size, in addition to the characteristic according to the fifth aspect of the present invention.
The electron microscope according to a fourteenth aspect of the present invention is characterized by the fact that it further comprises:
an automatic adjustment section for automatically adjusting an observation magnification of the observation image displayed on the first display section or the second display section to a magnification for enabling the whole of the specimen to be displayed, in addition to the characteristic according to the first aspect of the present invention.
Further, in order to accomplish the object above, according to a fifteenth aspect of the present invention, there is provided an electron microscope comprising:
an electron gun for applying an electron beam;
a gun alignment coil for making a correction to the electron beam applied from the electron gun so that the electron beam passes through the center of a lens system;
a converging lens for narrowing down a size of a spot of the electron beam;
an electron beam deflection scanning coil for scanning the electron beam converged through the converging lens over a specimen;
a detector for detecting secondary electrons or reflection electrons output from the specimen with scanning;
a display section for displaying an observation image based on the secondary electrons or the reflection electrons; and
a guidance section for guiding an operator through a setting procedure of a setup item required for setting at least an acceleration voltage or spot size as an image observation condition.
The electron microscope according to a sixteenth aspect of the present invention is characterized by the fact that the guidance section prompts the operator to select or enter a setup item to be set in an interactive mode and determines a necessary setup item based on the setting by the operator, in addition to the characteristic according to the fifteenth aspect of the present invention.
The electron microscope according to a seventeenth aspect of the present invention is characterized by the fact that the guidance section comprises an explanation display section for explaining selection or entry of a setup item to be set and for displaying an explanation about the setup item to be set, in addition to the characteristic according to the fifteenth aspect of the present invention.
The explanation display section can explain the setup item in text, an image, or voice or a combination thereof.
The electron microscope according to a eighteenth aspect of the present invention is characterized by the fact that the guidance section comprises:
a first setting section for selecting at least characteristics of the specimen as an image observation condition; and
an observation magnification change section for changing an observation magnification of an observation image of the specimen displayed on the display section based on the condition set through the first setting section, in addition to the characteristic according to the fifteenth aspect of the present invention.
The electron microscope according to a nineteenth aspect of the present invention is characterized by the fact that the display section comprises:
a first display section for displaying the observation image of the specimen based on the condition set through the first setting section; and
a second display section for displaying at least one observation image of the specimen including at least one secondary electron image or at least one reflection electron image under at least the acceleration voltage or the spot size changed at the observation magnification set through the observation magnification change section, in addition to the characteristic according to the eighteenth aspect of the present invention.
The electron microscope according to a twentieth aspect of the present invention is characterized by the fact that the guidance section comprises;
an observation positioning section for moving the observation image displayed on the first display section to a predetermined position on the first display section, in addition to the characteristic according to the nineteenth aspect of the present invention.
Further, in order to accomplish the object above, according to a twenty-first aspect of the present invention, there is provided a method for operating an electron microscope for picking up an observation image of a specimen based on an image observation condition, the method comprising:
setting at least characteristics of the specimen as an image observation condition on a first image observation mode screen;
displaying an observation image of the specimen on a first display section based on the condition set through the setting step;
displaying at least one observation image of the specimen including at least one secondary electron image or at least one reflection electron image under at least two types of image observation conditions based on the condition set through the setting step; and
selecting a desired observation image from among the observation images displayed on the second display section.
The electron microscope may further comprises:
moving the observation image displayed on the first display section to a predetermined position on the first display section; and
determining an observation magnification of the observation image displayed on the first display section,
wherein the at least one observation image of the specimen is displayed on the second display section at the determined observation position and observation magnification.
Further, it may further comprises:
moving the observation image displayed on the first display section to a predetermined position on the first display section; and
adjusting the observation magnification of the observation image displayed on the first display section,
wherein the at least one observation image of the specimen is displayed on the second display section at the adjusted observation magnification.
The electron microscope according to a twenty-second aspect of the present invention is characterized by the fact that it further comprises:
selecting either the first image observation mode screen or a second image observation mode screen as a screen for setting an image observation condition; and
setting at least a spot size of an electron beam on the specimen, an acceleration voltage, a detector type, a specimen position, and an observation magnification when the second image observation mode screen is selected, in addition to the characteristic according to the twenty-first aspect of the present invention.
The electron microscope according to a twenty-third aspect of the present invention is characterized by the fact that the at least two types of image observation conditions include at least two types of acceleration voltage or spot size changed, in addition to the characteristic according to the twenty-first aspect of the present invention.
The electron microscope according to a twenty-fourth aspect of the present invention is characterized by the fact that it further comprises:
selectively adjusting at least any of focus, contrast, or brightness with respect to the selected desired observation image, in addition to the characteristic according to the twenty-first aspect of the present invention.
The electron microscope according to a twenty-fifth aspect of the present invention is characterized by the fact that the moving step or the magnification adjusting step is automatically conducted based on a preset default value, in addition to the characteristic according to the twenty-first aspect of the present invention.
The electron microscope according to a twenty-sixth aspect of the present invention is characterized by the fact that the moving step moves a specimen table on which the specimen is placed, in addition to the characteristic according to the twenty-first aspect of the present invention.
The electron microscope according to a twenty-seventh aspect of the present invention is characterized by the fact that the moving step shifts a scan position of an electron beam applied from the electron gun, in addition to the characteristic according to the twenty-first aspect of the present invention.
The electron microscope according to a twenty-eight aspect of the present invention is characterized by the fact that it further comprises:
warning an operator that entry contents are erroneous, in addition to the characteristic according to the twenty-first aspect of the present invention.
The electron microscope according to a twenty-ninth aspect of the present invention is characterized by the fact that it further comprises:
setting a predetermined setup item as a limitation item which is inhibited from being set in each step, in addition to the characteristic according to the twenty-first aspect of the present invention.
The electron microscope according to a thirtieth aspect of the present invention is characterized by the fact that it further comprises:
setting a predetermined setup item which need not be set as nondisplay setup item in each step, in addition to the characteristic according to the twenty-first aspect of the present invention.
The electron microscope according to a thirty-first aspect of the present invention is characterized by the fact that the observation image displayed on the first display section is automatically moves roughly to the center on the first display section based on a preset default value, and the observation magnification of the observation image displayed on the first display section is automatically adjusted based on a preset default value, and wherein the at least one observation image of the specimen is displayed on the second display section at the adjusted observation magnification, in addition to the characteristic according to the twenty-first aspect of the present invention.
Further, according to a thirty-second aspect of the present invention, there is provided a computer-readable medium including a program executable on a computer for operating an electron microscope which picks up an observation image of a specimen based on an image observation condition, the program comprising instructions having:
a first function of selecting at least characteristics of the specimen as an image observation condition on a first image observation mode screen;
a second function of displaying an observation image of the specimen on a first display section based on the condition set through the first function;
a third function of moving the observation image displayed on the first display section to a predetermined position on the first display section;
a fourth function of changing an observation magnification of the observation image displayed on the first display section;
a fifth function of displaying at least one observation image of the specimen including at least one secondary electron image or at least one reflection electron image on a second display section under at least two types of image observation conditions at the observation position and the observation magnification set through the third and fourth functions; and
a sixth function of selecting a desired observation image from among the observation images displayed on the second display section.
The electron microscope according to a thirty-third aspect of the present invention is characterized by the fact that it further comprises:
a seventh function of switching a screen for setting an image observation condition between a second image observation mode screen and the first image observation mode screen; and
a eighth function of setting at least a spot size of an electron beam on the specimen, an acceleration voltage, a detector type, a specimen position, and an observation magnification on the second image observation mode screen, in addition to the characteristic according to the thirty-third aspect of the present invention.
The medium includes a magnetic disk, an optical disk, a magneto-optical disk, semiconductor memory, or any other medium capable of storing a program, such as CD-ROM, CD-R, CD-RW, flexible disk, magnetic tape, MO, DVD-ROM, DVD-RAM, DVD-R, DVD-RW, OR DVD+RW.
To observe under an electron microscope such as a SEM, steps indispensable for operation, such as searching for a visual field and condition setting, exist. The invention focuses attention on this point; necessary steps are explained for each screen and the operator is guided stepwise in operating the electron microscope for simplifying the operation of the electron microscope. To guide the operator in operating the electron microscope, flow form or wizard form can be used. A plurality of screens are provided in response to the setup item and are switched in order for display, whereby the operator is requested to enter condition required for image observation in a general way. Explanation is displayed for each screen and the item which needs to be specified on the screen is explained for the operator and the operator is also prompted to enter or select. Based on the entered information, each setup value is computed or the default value is entered as required for automatically setting necessary items. The operable range or items can also be limited for each screen for preventing erroneous entry or malfunction. In addition to the auto observation mode thus guiding the operator through the operation procedure, a manual observation mode for the operator to set all setup items is also provided and the operator can switch the auto and manual observation modes as he or she desires.